Criticality and Requirement Aware Heterogeneous Coherence for Mixed Criticality Systems

We propose $\mathsf{CoHoRT}$, as the first heterogeneous cache coherent solution for mixed criticality systems (MCS) equipped with several features that targets the characteristics and requirements of such systems. $\mathsf{CoHoRT}$ is requirement-aware. It provides an optimization engine to optimally configure the architecture based on system requirements. $\mathsf{CoHoRT}$ is also criticality-aware. It introduces a low-cost novel architecture to enable cores to heterogeneously run different coherence protocols (time-based and MSI-based protocols). Moreover, it enables a run-time switch between these protocols to provide hardware support for mode operation switch, which is a common chal-lenge in MCS. Our evaluation shows that $\mathsf{CoHoRT}$ outperforms existing solutions both from worst-case memory latency as well as overall average performance. It also illustrates that $\mathsf{CoHoRT}$ is able to meet timing requirements in various MCS setups and showcases $\mathsf{CoHoRT}$'s ability to adapt to mode switches.